It was said among the Elves, that Morgoth went there and put a darkness in the hearts of the Men.[4] Some Men, who were at war with those who fell under the Shadow, fled Hildórien seeking the Light of the West.[5]

In The Book of Lost Tales, Men awoke in a hidden valley called Murmenalda, the Vale of Sleep or Slumbrous Dale. It was enclosed by a wall of encircling mountains, east of Palisor, described as "hallowed" and full of sweet fragrances and odours, and songs of nightingales, its beauty being comparable to Valinor. It was full of sleeping figures.

It was discovered by the Dark ElfNuin after finding a passage through the mountain wall. Nuin almost swooned at its loveliness and was puzzled by the Sleepers. Despite Tu's warnings, Nuin visited it often to watch the Sleepers until, overcome with curiosity, he woke the first pair of them.[7]